Muscle stiffness indicating mission crew health in space

Abstract

Muscle function is compromised by gravitational unloading in space affecting overall musculoskeletal health. Astronauts perform daily exercise programmes to mitigate these effects but knowing which muscles to target would optimise effectiveness. Accurate inflight assessment to inform exercise programmes is critical due to lack of technologies suitable for spaceflight. Changes in mechanical properties indicate muscle health status and can be measured rapidly and non-invasively using novel technology. A hand-held MyotonPRO device enabled monitoring of muscle health for the first time in spaceflight (> 180 days). Greater/maintained stiffness indicated countermeasures were effective. Tissue stiffness was preserved in the majority of muscles (neck, shoulder, back, thigh) but Tibialis Anterior (foot lever muscle) stiffness decreased inflight vs. preflight (p < 0.0001; mean difference 149 N/m) in all 12 crewmembers. The calf muscles showed opposing effects, Gastrocnemius increasing in stiffness Soleus decreasing. Selective stiffness decrements indicate lack of preservation despite daily inflight countermeasures. This calls for more targeted exercises for lower leg muscles with vital roles as ankle joint stabilizers and in gait. Muscle stiffness is a digital biomarker for risk monitoring during future planetary explorations (Moon, Mars), for healthcare management in challenging environments or clinical disorders in people on Earth, to enable effective tailored exercise programmes.

Impact of Standing and Sitting Postures on Spinal Curvature and Muscle Mechanical Properties in Young Women: A Photogrammetric and MyotonPro Analysis

“…Please note that MyotonPRO technology is used to assess the mechanical properties of superficial muscles, tendons, and fascia [ 12 ]. The points we chose corresponded with those chosen by others, which most often relate to the properties of such structures as: for the cervical region, the cervical muscle [ 11 ], splenius capitis [ 31 ], or simply the neck region [ 32 ]; for the thoracic region, the trapezius muscle [ 8 – 10 ]; and for the lumbar region, the lumbar multifidus [ 31 ] or lumbar erector spinae [ 12 ], which is also called the lumbar spine [ 32 ] or lumbar muscle [ 11 , 12 , 15 , 34 , 35 , 41 ].…”